1. Field
Apparatuses and methods consistent with exemplary embodiments relate to a backlight unit and a display apparatus, and more particularly, to a backlight unit which displays an image using backlight radiated from a light emitting module of a display and a display apparatus having the same.
2. Description of the Related Art
A liquid crystal display (LCD) which is widely used cannot emit light for itself. Therefore, an LCD panel needs to have a backlight unit which provides backlight to the LCD.
The backlight unit includes a light emitting unit which generates the backlight and a light guide plate which uniformly transmits the backlight radiated from the light emitting unit onto a panel surface of the LCD.
The light emitting unit includes light emitting elements which are disposed in order to efficiently provide the backlight to the LCD and a driving element which drives the light emitting elements. A proper number of driving elements are provided to drive the light emitting elements without any problems.
A display apparatus employs a method for adjusting the luminance of the backlight using a dimming control in order to enhance a contrast ratio of a display screen and to reduce power consumption. There are two kinds of the dimming control methods: the pulse width modulation (PWM) control method and the analog dimming control method.
The analog dimming control method adjusts the luminance of the backlight by controlling the amount of current applied to a light emitting unit. That is, if it is desired to decrease a brightness of the backlight by half, the display apparatus may reduce the amount of current applied to the light emitting unit by half to adjust the brightness.
The PWM control method adjusts the luminance of the backlight by controlling ON/OFF switching of the light emitting unit. That is, if a PWM signal having an ON/OFF ratio of 4 to 1 is provided to the light emitting unit, the light emitting unit may present a maximum of 80% brightness.
Since the analog dimming control method is disadvantageous in that it is difficult to adjust the luminance using a low current, a display apparatus adjusts the luminance of the backlight using a PWM control method. However, even if luminance of backlight is adjusted using the PWM control method, the luminance representation may be deteriorated in a low grayscale region since it is impossible for a dimming frequency to be increased limitlessly.
Therefore, there is a need for methods which enhance luminance representation of backlight.